Frequent or contextually predictable words are often phonetically reduced, i.e. shortened and produced with articulatory undershoot. Explanations for phonetic reduction of predictable forms tend to take one of two approaches: Intelligibility-based accounts hold that talkers maximize intelligibility of words that might otherwise be difficult to recognize; productionbased accounts hold that variation reflects the speed of lexical access and retrieval in the language production system. Here we examine phonetic variation as a function of phonological neighborhood density, capitalizing on the fact that words from dense phonological neighborhoods tend to be relatively difficult to recognize, yet easy to produce.We show that words with many phonological neighbors tend to be phonetically reduced (shortened in duration and produced with more centralized vowels) in connected speech, when other predictors of phonetic variation are brought under statistical control. We argue that our findings are consistent with the predictions of production-based accounts of pronunciation variation.

This study tested the hypothesis that heritage speakers of a minority language, due to their childhood experience with two languages, would outperform late learners in producing contrast: language-internal phonological contrast, as well as cross-linguistic phonetic contrast between similar, yet acoustically distinct, categories of different languages. To this end, production of Mandarin and English by heritage speakers of Mandarin was compared to that of native Mandarin speakers and native American English-speaking late learners of Mandarin in three experiments. In Experiment 1, back vowels in Mandarin and English were produced distinctly by all groups, but the greatest separation between similar vowels was achieved by heritage speakers. In Experiment 2, Mandarin aspirated and English voiceless plosives were produced distinctly by native Mandarin speakers and heritage speakers, who both put more distance between them than late learners. In Experiment 3, the Mandarin retroflex and English palato-alveolar fricatives were distinguished by more heritage speakers and late learners than native Mandarin speakers. Thus, overall the hypothesis was supported: across experiments, heritage speakers were found to be the most successful at simultaneously maintaining language-internal and cross-linguistic contrasts, a result that may stem from a close approximation of phonetic norms that occurs during early exposure to both languages.

In this paper we propose some new measures of language development using network analyses, which is inspired by the recent surge of interests in network studies of many real-world systems. Children's and care-takers' speech data from a longitudinal study are represented as a series of networks, word forms being taken as nodes and collocation of words as links. Measures on the properties of the networks, such as size, connectivity, hub and authority analyses, etc., allow us to make quantitative comparison so as to reveal different paths of development. For example, the asynchrony of development in network size and average degree suggests that children cannot be simply classified as early talkers or late talkers by one or two measures. Children follow different paths in a multi-dimensional space. They may develop faster in one dimension but slower in another dimension. The network approach requires little preprocessing of words and analyses on sentence structures, and the characteristics of words and their usage emerge from the network and are independent of any grammatical presumptions. We show that the change of the two articles "the" and "a" in their roles as important nodes in the network reflects the progress of children's syntactic development: the two articles often start in children's networks as hubs and later shift to authorities, while they are authorities constantly in the adult's networks. The network analyses provide a new approach to study language development, and at the same time language development also presents a rich area for network theories to explore. children use certain constructions often as formulaic expressions, instead of knowing the constructions are decomposable as adults do (Peters, 1977;Wray, 2002).In this paper, we propose a novel approach to analyze the language development from a network perspective. We take the children's longitudinal speech data to construct lexical networks at different stages, and compare these networks with several measures. Also, we compare networks between different children, and networks between children and their caretakers. Through the comparison, children's development and individual differences can be demonstrated quantitatively by measures with little language-specific assumptions.

Whether tone language experience facilitates non-native tone perception is an area of research that previously yielded conflicting results, potentially because of the lack of systematical control of speaker normalization effects across studies. Under a high-variability testing condition with controlled speaker normalization cues, Cantonese (native controls), Mandarin (Cantonese-naive tone listeners), and English (non-tone listeners) listeners identified three Cantonese level tones. The results indicate a facilitatory effect of tone experience on non-native tone perception when normalization for inter-speaker variation is required.

Phonological neighborhood effects have been found in spoken word recognition, word production and phonetic variation (Gahl, Yao, & Johnson, 2012; Luce & Pisoni, 1998; Vitevitch, 2002). Overall, words from dense neighborhoods are harder to recognize but easier to produce. However, most previous studies have focused on English, while evidence suggests that these effects may not generalize cross-linguistically due to language-specific configurations of the lexicon (Michael S Vitevitch & Stamer, 2006, 2009). In the current study, we investigate the effects of phonological neighborhoods in Mandarin Chinese, which has a vastly different lexicon structure from that of English. Results from an auditory lexical decision experiment showed that phonological neighborhood density and neighbor frequency (defined by the one-phoneme/tone difference rule) are predictive of the speed and accuracy of lexical decision. Homophone density also has a facilitative effect on the accuracy of lexical decision. The implications of the current findings are discussed in the framework of the lexicon model proposed by Zhou & Marslen-Wilson (1994, 2009).